arch/arm/mach-bcm/bcm_kona_smc.c

   1 /*
   2  * Copyright (C) 2013 Broadcom Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License as
   6  * published by the Free Software Foundation version 2.
   7  *
   8  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
   9  * kind, whether express or implied; without even the implied warranty
  10  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <stdarg.h>
  15 #include <linux/smp.h>
  16 #include <linux/io.h>
  17 #include <linux/ioport.h>
  18
  19 #include <asm/cacheflush.h>
  20 #include <linux/of_address.h>
  21
  22 #include "bcm_kona_smc.h"
  23
  24 static u32              bcm_smc_buffer_phys;    /* physical address */
  25 static void __iomem     *bcm_smc_buffer;        /* virtual address */
  26
  27 struct bcm_kona_smc_data {
  28         unsigned service_id;
  29         unsigned arg0;
  30         unsigned arg1;
  31         unsigned arg2;
  32         unsigned arg3;
  33         unsigned result;
  34 };
  35
  36 static const struct of_device_id bcm_kona_smc_ids[] __initconst = {
  37         {.compatible = "brcm,kona-smc"},
  38         {.compatible = "bcm,kona-smc"}, /* deprecated name */
  39         {},
  40 };
  41
  42 /* Map in the args buffer area */
  43 int __init bcm_kona_smc_init(void)
  44 {
  45         struct device_node *node;
  46         const __be32 *prop_val;
  47         u64 prop_size = 0;
  48         unsigned long buffer_size;
  49         u32 buffer_phys;
  50
  51         /* Read buffer addr and size from the device tree node */
  52         node = of_find_matching_node(NULL, bcm_kona_smc_ids);
  53         if (!node)
  54                 return -ENODEV;
  55
  56         prop_val = of_get_address(node, 0, &prop_size, NULL);
  57         if (!prop_val)
  58                 return -EINVAL;
  59
  60         /* We assume space for four 32-bit arguments */
  61         if (prop_size < 4 * sizeof(u32) || prop_size > (u64)ULONG_MAX)
  62                 return -EINVAL;
  63         buffer_size = (unsigned long)prop_size;
  64
  65         buffer_phys = be32_to_cpup(prop_val);
  66         if (!buffer_phys)
  67                 return -EINVAL;
  68
  69         bcm_smc_buffer = ioremap(buffer_phys, buffer_size);
  70         if (!bcm_smc_buffer)
  71                 return -ENOMEM;
  72         bcm_smc_buffer_phys = buffer_phys;
  73
  74         pr_info("Kona Secure API initialized\n");
  75
  76         return 0;
  77 }
  78
  79 /*
  80  * int bcm_kona_do_smc(u32 service_id, u32 buffer_addr)
  81  *
  82  * Only core 0 can run the secure monitor code.  If an "smc" request
  83  * is initiated on a different core it must be redirected to core 0
  84  * for execution.  We rely on the caller to handle this.
  85  *
  86  * Each "smc" request supplies a service id and the address of a
  87  * buffer containing parameters related to the service to be
  88  * performed.  A flags value defines the behavior of the level 2
  89  * cache and interrupt handling while the secure monitor executes.
  90  *
  91  * Parameters to the "smc" request are passed in r4-r6 as follows:
  92  *     r4       service id
  93  *     r5       flags (SEC_ROM_*)
  94  *     r6       physical address of buffer with other parameters
  95  *
  96  * Execution of an "smc" request produces two distinct results.
  97  *
  98  * First, the secure monitor call itself (regardless of the specific
  99  * service request) can succeed, or can produce an error.  When an
 100  * "smc" request completes this value is found in r12; it should
 101  * always be SEC_EXIT_NORMAL.
 102  *
 103  * In addition, the particular service performed produces a result.
 104  * The values that should be expected depend on the service.  We
 105  * therefore return this value to the caller, so it can handle the
 106  * request result appropriately.  This result value is found in r0
 107  * when the "smc" request completes.
 108  */
 109 static int bcm_kona_do_smc(u32 service_id, u32 buffer_phys)
 110 {
 111         register u32 ip asm("ip");      /* Also called r12 */
 112         register u32 r0 asm("r0");
 113         register u32 r4 asm("r4");
 114         register u32 r5 asm("r5");
 115         register u32 r6 asm("r6");
 116
 117         r4 = service_id;
 118         r5 = 0x3;               /* Keep IRQ and FIQ off in SM */
 119         r6 = buffer_phys;
 120
 121         asm volatile (
 122                 /* Make sure we got the registers we want */
 123                 __asmeq("%0", "ip")
 124                 __asmeq("%1", "r0")
 125                 __asmeq("%2", "r4")
 126                 __asmeq("%3", "r5")
 127                 __asmeq("%4", "r6")
 128                 ".arch_extension sec\n"
 129                 "       smc    #0\n"
 130                 : "=r" (ip), "=r" (r0)
 131                 : "r" (r4), "r" (r5), "r" (r6)
 132                 : "r1", "r2", "r3", "r7", "lr");
 133
 134         BUG_ON(ip != SEC_EXIT_NORMAL);
 135
 136         return r0;
 137 }
 138
 139 /* __bcm_kona_smc() should only run on CPU 0, with pre-emption disabled */
 140 static void __bcm_kona_smc(void *info)
 141 {
 142         struct bcm_kona_smc_data *data = info;
 143         u32 __iomem *args = bcm_smc_buffer;
 144
 145         BUG_ON(smp_processor_id() != 0);
 146         BUG_ON(!args);
 147
 148         /* Copy the four 32 bit argument values into the bounce area */
 149         writel_relaxed(data->arg0, args++);
 150         writel_relaxed(data->arg1, args++);
 151         writel_relaxed(data->arg2, args++);
 152         writel(data->arg3, args);
 153
 154         /* Flush caches for input data passed to Secure Monitor */
 155         flush_cache_all();
 156
 157         /* Trap into Secure Monitor and record the request result */
 158         data->result = bcm_kona_do_smc(data->service_id, bcm_smc_buffer_phys);
 159 }
 160
 161 unsigned bcm_kona_smc(unsigned service_id, unsigned arg0, unsigned arg1,
 162                   unsigned arg2, unsigned arg3)
 163 {
 164         struct bcm_kona_smc_data data;
 165
 166         data.service_id = service_id;
 167         data.arg0 = arg0;
 168         data.arg1 = arg1;
 169         data.arg2 = arg2;
 170         data.arg3 = arg3;
 171         data.result = 0;
 172
 173         /*
 174          * Due to a limitation of the secure monitor, we must use the SMP
 175          * infrastructure to forward all secure monitor calls to Core 0.
 176          */
 177         smp_call_function_single(0, __bcm_kona_smc, &data, 1);
 178
 179         return data.result;
 180 }